DE 10 2006 034 756 A1 and DE 10 2009 010 561 A1 each describe a medical instrument for cutting tissue. A tubular inner shank rotates inside a tubular outer shank. Outer shank and inner shank each have windows with blades. Tissue that is cut off by interaction of the blades on the outer shank and on the inner shank is sucked out through the inner shank.
Especially when removing bone tissue or other hard and/or tough tissue, medical personnel often apply considerable forces and torques to the proximal end of the medical instrument in order to press the distal end, for example, with the greatest possible force against a tissue surface that is to be worked. These forces and torques can deform the medical instrument (in general elastically) and in particular bend a shank of the medical instrument.
The described deformation of the medical instrument and/or other causes can have the effect that the inner shank is displaced or tilted with respect to its intended position relative to the outer shank. The inner shank and the outer shank can thus touch each other in a way that is not intended. Contact between the inner shank and the outer shank, in particular between the blades on the inner shank and outer shank, can increase the wear of both and can cause abrasion in the form of fine particles or even the breaking-off of larger particles.
Particles generated in the described manner, or in some other way, are foreign bodies that should not remain at the operating site. The particles are sucked or scraped off, for example, with or without the use of a flushing liquid. With a suitable choice of the materials of the medical instrument, it is true that particles nonetheless remaining in the operating site do not have any toxic effect. However, the particles can have a mechanically disadvantageous effect and can, for example, cause artefacts in subsequent X-rays. Abrasion of medical instruments and the avoidance and/or removal of the abraded material are therefore challenges that still have to be tackled.